In the United States of America juicy objects, such as pickles, are usually packed by use mainly of bottles or cans. Some business men in the field concerned are eager to employ a bag for packing such kind of objects because bags are cheaper to produce than bottles and cans. But, when the bag is filled with objects, especially a liquid, and seated, the bag is unstable in comparison with the bottles and cans and cannot be seated well, so that bags are not fit for use in packing by the automatic packing device. Therefore, bottles and cans are widely employed at present.
U.S. Pat. Nos. 3,982,376 and 4,081,942 disclose a rotary system packing apparatus wherein bags kept in suspension by a mechanical clamp are conveyed in order to be filled with objects by a filling unit provided at a predetermined position, and thereafter, an opening portion of the bag is sealed at the next stage. The inventor has given notice that a vacuum chamber is incorporated into such conventional apparatus, and each mechanical clamp is moved integrally with the vacuum chamber, so that the juicy objects with a liquid may be vacuum packed mechanically by use of even bags of poor stability in setting as aforesaid. But, a simple technical conception merely given to the apparatus only produces a bad economy and leads to various problems. An imaginative possible construction of such type of vacuum-packing apparatus may comprise a section for feeding a bag to the clamp, a section for opening the mouth of the bags and fitting therein a liquid and objects, a section for applying a vacuum inside the bags, a section for sealing the opening portion thereof, and a section for removing the sealed bags from the clamps. The vacuum chambers must be open at all sections other than the section for applying the vacuum inside the bag and the section for sealing the opening portions of the bags. In other words, it is natural that the vacuum chambers do not at all function or work at the sections where the chambers are open, so that such sections do not need any vacuum chamber. Furthermore, in case the bags are employed for packing the objects together with a liquid, it is necessary to give special attention to the following points.
(1) When chopped objects like pickles chopped by a knife are filled, together with a liquid, into a bag which is then subjected to a vacuum, numerous bubbles rise up in the liquid toward the mouth of the bag corresponding to a drop of pressure. Some bubbles are caught by the chopped objects to be kept thereunder. The bags are often sealed with such bubbles being kept inside the bag. In case the bag is transparent, the kept bubbles are visible, so that such products are not preferable ones and deviate from a standard vacuum-packed product.
(2) A thin flexible bag is apt to be twisted or bent when it is fed to the clamp, so that when each of such bags is continuously caught by mechanical clamps, failure of catching of such bags often happens.